<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
    <script>
        function sayName(label){
            console.log(label+":"+this.name)
        }
        var cheng={
            name:'cheng'
        }
        var wang={
            name:"wang"
        }
        var name="window"
        sayName("window")
        sayName.call(cheng,"chengchao")//chengchao:cheng
        sayName.call(wang,"女孩子")
        </script>
</body>
</html>